This is Gertrude's lower trunk... The white stuff possibly a fungus??

Close up of leaves...

Well, looks to me like your potting soil is very soggy? Perhaps you have a potting medium that is holding on to too much water. And, the fungal infection on the trunk may indeed by just that - phytophthora. I would re-pot your tree with a better draining potting mix. There are a couple of good recipes on the forum, search for "511 mix" or "gritty mix". Or, if you have access to Farfard Professional potting mixes by the bag, they have a couple of great choices. Again, search our forum for "farfard" for which of the professional mixes our container citrus folks have used successfully. I then would treat your tree with phosphorus acid (AgriFos), which you can find online. I believe I bought mine through amazon.com. It is organic, and works extremely well to get rid of this soil pathogen than can affect both the trunk and roots of citrus trees. I would also spray the affected trunk area with a coppyer fungicide (can be picked up at any good garden center). You usually see this with in-ground trees, but if your conditions are wet enough, and you've used soil in your pot, it can also occur in container citrus. Don't be surprised if your little tree drops most or all of its leaves. But, don't dismay, once repotted and treated, continue to water appropriately and fertilize regularly to encourage a new flush of leaves. It should happen for you, and I would encourage you to do this right away, so you can take advantage of the last of your warm outdoor weather to get the tree recovering before you have to pull it inside for the winter.

Patty S.

Thanks Patty! I will try these solutions and let you know how she does...

Paul